Method for producing high-protein milk raw material

Abstract

Provided is a method for producing a milk raw material having a high protein content (a high-protein milk raw material), particularly a method for producing a high-protein milk raw material having an improved flavor. Said production method comprises: (1) a step for preparing, from a milk raw material, a milk fluid having 5-15 mass% of a total solid content and at least 50 parts by mass a milk-derived protein content per 100 parts by mass of the total solid content; and (2) a step for adding lactobacillus to the milk fluid, maintaining the milk fluid until the pH reaches 5.2-6.5, and obtaining the lactobacillus-treated milk fluid that falls within said pH range.

Description

Manufacturing method for high-protein dairy ingredients REFERENCE TO RELATED APPLICATIONS

[0001] This application claims priority based on Japanese Patent Application No. 2022-146502, filed on September 14, 2022, the entire disclosure of which is incorporated herein by reference.

[0002] The present invention relates to a method for producing a dairy raw material having a high protein content (referred to as a "high-protein dairy raw material" in the present invention). The present invention also relates to a high-protein dairy raw material with improved flavor. The present invention further relates to a food or beverage containing the high-protein dairy raw material and a method for producing the same. The present invention still further relates to a method for improving the flavor of a high-protein dairy raw material.

[0003] For example, high-protein dairy ingredients such as milk protein concentrate (MPC) and whey protein concentrate (WPC), which contain 50% by mass or more of milk-derived protein (hereinafter referred to as "milk-derived protein"), have a protein odor specific to milk-derived proteins. Therefore, when these ingredients are blended in a predetermined amount into a food or beverage, the flavor of the food or beverage may be impaired.

[0004] To improve this, a method has been proposed in which the casein odor derived from milk proteins is masked by adding amino acids and / or sweeteners such as glycine and / or aspartame to a protein-containing beverage (Patent Document 1). However, because glycine and aspartame are both sweet substances, depending on the amount added, they may affect or impair the flavor of the protein-containing beverage.

[0005] As another method, a method of contacting a high-protein milk fluid having a protein content of 60% by mass or more relative to the total solid content with activated carbon and a method of concentrating the milk fluid using a nanofiltration membrane have been proposed (Patent Documents 2 and 3). Although these methods are useful as methods for obtaining a high-protein milk raw material with a reduced milk-derived protein odor and an improved refreshing taste, they require equipment such as an activated carbon column filter and a membrane module unit.

[0006] Meanwhile, methods using fermentation techniques are known as methods for masking odors. For example, Patent Document 4 describes a method for masking the aloe-derived odor of aloe-containing fermented milk, in which a fermented milk base prepared by fermenting a fermented milk raw material containing Bifidobacterium bacteria and a lactic acid bacteria starter until the pH reaches 4.4 to 4.8 is mixed with a predetermined amount of an aloe gel dispersion, and describes that this method can reduce the grassy odor characteristic of aloe gel. Furthermore, Patent Document 5 describes a method for reducing the grassy odor, bitterness, and astringent taste that are specific to soybeans in lactic acid-fermented soy milk foods, in which soy milk is fermented using one or more lactic acid bacteria strains selected from Lactobacillus paracasei tolerance N-5 strain (accession number NITE P-02630), Lactococcus lactis holdoniae Lhana strain (accession number NITE P-02631), and Lactobacillus pentosus Lpome-3 strain (accession number NITE P-02632) as a lactic acid bacteria starter used in the production of lactic acid-fermented soy milk foods, and describes that by doing so, the unpleasant odor (grassy odor) and unpleasant taste (bitterness and astringent taste) that are specific to soybeans can be suppressed.

[0007] JP 2020-141559 A International Publication No. WO2020 / 085517 International Publication No. WO2020 / 085518 JP 2017-176030 A Japanese Patent Application Laid-Open No. 2019-165667 A

[0008] The first object of the present invention is to provide a method for producing a dairy raw material having a high protein content (high-protein dairy raw material). Preferably, the method is to provide a method for producing a high-protein dairy raw material in which the generation of a protein odor caused by milk-derived proteins (hereinafter referred to as "milk-derived protein odor") is suppressed. The second object of the present invention is to provide a high-protein dairy raw material obtained by treatment with lactic acid bacteria (hereinafter referred to as "lactic acid bacteria-treated high-protein dairy raw material"). Preferably, the method is to provide a lactic acid bacteria-treated high-protein dairy raw material in which the milk-derived protein odor is suppressed. A third object of the present invention is to provide a new food or beverage containing the lactic acid bacteria-treated high-protein dairy raw material, and a method for producing the same. A fourth object of the present invention is to provide a method for improving the flavor of a high-protein dairy raw material in which the generation of a milk-derived protein odor is suppressed.

[0009] The present inventors have conducted extensive research to solve the above problems and have found that by preparing a milk fluid from a milk raw material having a total solid content of 5 to 15 mass % and a milk-derived protein content of 50 mass parts or more per 100 mass parts of total solid content, and then maintaining this using lactic acid bacteria until the pH is in the range of 5.2 to 6.5 (excluding the pH range in which curd is formed) (lactic acid bacteria treatment), the protein odor caused by the milk-derived protein (milk-derived protein odor) can be suppressed compared to high-protein milk raw materials prepared without lactic acid bacteria treatment, and a high-protein milk raw material with improved flavor can be obtained.

[0010] The present invention was completed based on these findings and through further investigation, and has the following embodiments. (I) Method for producing high-protein milk raw material (I-1) A method for producing a high-protein milk raw material, comprising: (1) preparing a milk fluid from a milk raw material, the milk fluid having a total solids content of 5 to 15% by mass and a milk-derived protein content of 50 parts by mass or more per 100 parts by mass of the total solids, and (2) adding lactic acid bacteria to the milk fluid and maintaining the pH until the pH falls within the range of 5.2 to 6.5 (lactic acid bacteria treatment), to obtain a lactic acid bacteria-treated milk fluid having a pH within the range. (I-2) A method for producing a high-protein milk raw material as described in (I-1), further comprising: (3-1) concentrating the lactic acid bacteria-treated milk fluid, or concentrating and drying the lactic acid bacteria-treated milk fluid. (I-3) A method for producing a high-protein milk raw material as described in (I-1), further comprising: (3-2) drying the lactic acid bacteria-treated milk fluid. (I-4) A method for producing a high-protein milk raw material according to any one of (I-1) to (I-3), wherein the milk fluid does not contain casein but contains whey protein as the milk-derived protein. (I-5) A method for producing a high-protein milk raw material according to any one of (I-1) to (I-3), wherein the milk fluid contains casein or casein and whey protein as the milk-derived protein, and the step (2) is a step of maintaining the pH using lactic acid bacteria until the pH is in the range of 6.0 to 6.5 (lactic acid bacteria treatment) to obtain a lactic acid bacteria-treated milk fluid having a pH in that range. (I-6) A production method according to (I-4), wherein the high-protein milk raw material is at least one selected from whey protein concentrate (WPC) and whey protein isolate (WPI). Note that these WPC and WPI have been treated with lactic acid bacteria. (I-7) The production method according to (I-5), wherein the high-protein dairy raw material is at least one selected from the group consisting of milk protein concentrate (MPC), milk protein isolate (MPI), and micellar casein concentrate (MCC). Note that these MPC, MPI, and MCC are treated with lactic acid bacteria.(I-8) A method for producing a high-protein milk raw material according to any one of (I-1) to (I-7), which does not include a step of treating the milk fluid obtained in step (1) or the lactic acid bacteria-treated milk fluid obtained in step (2) with activated carbon. The production method of the present invention improves the flavor of the high-protein milk raw material by treating the milk fluid obtained in step (1) with lactic acid bacteria. For this reason, it is distinguished from techniques that attempt to improve flavor by removing impurities using activated carbon treatment, etc.

[0011] (II) High-protein milk raw material treated with lactic acid bacteria (II-1) A liquid high-protein milk raw material treated with lactic acid bacteria, having a milk-derived protein content of 50 parts by mass or more per 100 parts by mass of total solids, characterized in that the lactic acid bacteria-treated high-protein milk raw material contains at least killed lactic acid bacteria cells, diacetyl, and 3-hydroxy-2-butanone, and has a pH in the range of 5.2 to 6.5. (II-2) The high-protein milk raw material treated with lactic acid bacteria according to (II-1), which does not contain casein but contains whey protein as the milk-derived protein. (II-3) The high-protein milk raw material treated with lactic acid bacteria according to (II-1), which contains casein or casein and whey protein as the milk-derived protein, and has a pH in the range of 6.0 to 6.5. (II-4) A semi-solid or solid lactic acid bacteria-treated high-protein milk raw material obtained by concentrating and / or drying a liquid lactic acid bacteria-treated high-protein milk raw material described in any one of (II-1) to (II-3).

[0012] (III) Food and drink products and their manufacturing method (III-1) A manufacturing method for a food and drink product, comprising a step of incorporating a high-protein milk raw material obtained by the manufacturing method described in any one of (I-1) to (I-8) into a food and drink product. (III-2) A food and drink product containing a lactic acid bacteria-treated high-protein milk raw material described in any one of (II-1) to (II-4).

[0013] (IV) Method for improving the flavor of high-protein dairy raw materials (IV-1) A method for improving the flavor of high-protein dairy raw materials, comprising: (1) a step of preparing a dairy fluid from the dairy raw materials, the dairy fluid having a total solid content of 5 to 15 mass % and a milk-derived protein content of 50 mass parts or more per 100 mass parts of the total solid content; and (2) a step of adding lactic acid bacteria to the dairy fluid and maintaining the pH until it falls within the range of 5.2 to 6.5 (lactic acid bacteria treatment), thereby obtaining a lactic acid bacteria-treated dairy fluid having a pH within the range.

[0014] The high-protein milk raw material produced by the production method of the present invention has a significantly reduced milk-derived protein odor compared to a high-protein milk raw material that has not been treated with lactic acid bacteria. Therefore, according to the present invention, a high-protein milk raw material having a reduced milk-derived protein odor and improved flavor can be provided. Furthermore, despite containing a high proportion of milk-derived protein of 50 parts by mass or more per 100 parts by mass of total solids, the milk-derived protein odor is reduced, so the high-protein milk raw material can be added to foods and beverages without impairing flavor. Furthermore, according to the flavor improvement method of the present invention, the milk-derived protein odor of the high-protein milk raw material can be significantly reduced compared to a high-protein milk raw material that has not been treated with lactic acid bacteria.

[0015] (I) Method for Producing High-Protein Milk Raw Material The production method of the present invention is characterized by comprising at least the following steps: (1) a step of preparing a milk fluid from a milk raw material having a total solids content of 5 to 15% by mass and a milk-derived protein content of 50 parts by mass or more per 100 parts by mass of the total solids (hereinafter, this step is also referred to as the "milk fluid preparation step"); and (2) a step of adding lactic acid bacteria to the milk fluid and maintaining the pH in the range of 5.2 to 6.5 (lactic acid bacteria treatment) to obtain a lactic acid bacteria-treated milk fluid having a pH in the range (hereinafter, this step is also referred to as the "lactic acid bacteria treatment step"). The production method of the present invention can be said to be a method for producing a high-protein milk raw material in which the milk-derived protein odor is significantly reduced compared to a high-protein milk raw material not treated with lactic acid bacteria. Preferably, the production method of the present invention can be said to be a method for producing a high-protein milk raw material in which the milk-derived protein odor is significantly reduced compared to a high-protein milk raw material not treated with lactic acid bacteria and which has a refreshing aftertaste (improved refreshing feeling). In particular, the production method of the present invention, in which a pH of 6.0 to 6.5 is employed in the lactic acid bacteria treatment step, can be said to be a method for producing a high-protein milk raw material in which the milk-derived protein odor is significantly suppressed, the aftertaste is clean (improved cleanliness), and there is no perceived sourness (no sourness), compared to a high-protein milk raw material that is not treated with lactic acid bacteria.

[0016] (1) Milk Fluid Preparation Step The "milk raw material" used as a starting raw material in the milk fluid preparation step is a raw material for preparing a milk fluid having a total solids content of 5 to 15% by mass and a milk-derived protein content of 50 parts by mass or more per 100 parts by mass of total solids, and to that extent, it is sufficient that it contains at least a milk-derived protein as a milk component. As long as the effects of the present invention are not impaired, other milk components may also be contained, such as milk fat, lactose, and / or ash. The form of the "milk raw material" is not particularly limited, and may be, for example, a fluid such as a liquid or semi-solid (e.g., gel), or may be a dried solid (powder, granules, granules, tablet (pill), etc.) containing a milk component.

[0017] Examples of the "dairy ingredient" include raw milk squeezed from cows, cow's milk (whole milk), skim milk, whole milk powder, skim milk powder, whole fat concentrated milk, skim milk concentrated, whey, whey powder, desalted whey, desalted whey powder, whey protein concentrate (WPC), whey protein isolate (WPI), milk protein concentrate (MPC), milk protein isolate (MPI), and micellar casein concentrate (MCC).

[0018] The "dairy raw material" is not particularly limited, but is preferably a dairy raw material having a high content of milk-derived protein relative to the total solid content, and specific examples include whey protein concentrate (WPC), whey protein isolate (WPI), milk protein concentrate (MPC), milk protein isolate (MPI), and micellar casein concentrate (MCC).

[0019] The "dairy fluid" prepared in the dairy fluid preparation step is characterized by having a total solid content of 5 to 15 mass % and a milk-derived protein content of 50 mass parts or more per 100 mass parts of total solid content. The dairy fluid includes liquid and semi-solid fluids containing milk-derived proteins at high concentrations.

[0020] As described above, the total solids content of the "dairy fluid" may be in the range of 5 to 15% by mass, preferably 6 to 14% by mass, more preferably 7 to 13% by mass, and even more preferably 8 to 12% by mass. Here, the "total solids content" refers to the proportion of the total amount of solids contained in 100% by mass of the dairy fluid. Here, the total solids include milk components contained in the dairy fluid (for example, milk-derived proteins, milk fat, carbohydrates, and ash).

[0021] As described above, the content of milk-derived protein per 100 parts by mass of the total solids contained in the "dairy fluid" may be 50 parts by mass or more, preferably 60 parts by mass or more, more preferably 70 parts by mass or more, even more preferably 75 parts by mass or more, and particularly preferably 80 parts by mass or more. The upper limit is not limited, but an example of this is 95 parts by mass.

[0022] The "milk-derived protein content per 100 parts by mass of total solids" refers to the proportion (parts by mass) of milk-derived protein when the total amount of solids contained in the milk fluid is taken as 100 parts by mass. The total amount of solids contained in the milk fluid can be measured in accordance with ISO 6731 (IDF21 Milk - Determination of total solids content). The protein content in the milk fluid can be calculated by multiplying the nitrogen content measured by the combustion method or Kjeldahl method by the nitrogen-to-protein conversion factor.

[0023] The "dairy fluid" is not particularly limited, but is preferably a retentate obtained by treating cheese whey and / or acid whey with an ultrafiltration (UF) membrane, a permeate or retentate obtained by treating a retentate obtained by treating cheese whey and / or acid whey with an ultrafiltration (UF) membrane with a microfiltration (MF) membrane, a retentate obtained by treating whole fat milk and / or skim milk with an ultrafiltration (UF) membrane, a permeate or retentate obtained by treating a retentate obtained by treating whole fat milk and / or skim milk with an ultrafiltration (UF) membrane with a microfiltration (MF) membrane, a permeate or retentate obtained by treating whole fat milk and / or skim milk ... Examples of the retentate include whey protein concentrate (WPC: protein content of about 80% by mass of the total solids), whey protein isolate (WPI: protein content of about 90% by mass of the total solids), milk protein concentrate (MPC: protein content of about 80% by mass of the total solids), milk protein isolate (MPI: protein content of about 90% by mass of the total solids), and micellar casein concentrate (protein content of about 80% by mass of the total solids). In the above, the term "retentate" refers to a liquid (also referred to as a concentrated liquid) that is retained on the membrane and concentrated during membrane treatment without passing through the membrane, and the term "permeate" refers to a liquid that has permeated the membrane during membrane treatment. For example, by subjecting a retentate obtained by UF treatment of cheese whey and / or acid whey to MF membrane treatment, components other than whey protein are retained on the MF membrane, thereby obtaining a permeate with an increased whey protein concentration. Furthermore, by subjecting a retentate obtained by UF membrane treatment of whole milk and / or skim milk to protein concentration, a retentate selectively enriched in micellar casein and a permeate containing whey protein can be obtained.

[0024] The method for preparing the "milk fluid" from the "milk raw materials" is not particularly limited, as long as it is a method for preparing a milk fluid having a total solid content of 5 to 15 mass % and a milk-derived protein content of 50 mass parts or more per 100 mass parts of total solids by using one type or a combination of two or more types of the "milk raw materials." Examples of such a method include a method in which the "milk raw materials" are used as they are or two or more types are combined; a method in which the "milk raw materials" are dissolved (reduced) in water or hot water (warm water, hot water); a method in which the milk raw materials or their reduced products are further subjected to a defatting treatment followed by a membrane treatment, or a method in which the milk raw materials or their reduced products are further subjected to an acid treatment or an enzyme treatment followed by a membrane treatment.

[0025] The milk fluid thus prepared is preferably sterilized before being subjected to the lactic acid bacteria treatment step described below. The sterilization treatment may be carried out so as not to interfere with the lactic acid bacteria treatment described below, and is preferably carried out until the general bacterial count in the milk fluid is 1000 cfu / ml or less. The sterilization treatment may be any method and condition that can achieve this purpose, and is not particularly limited. Examples of heat treatment methods include those used for sterilizing milk, such as ultra-high temperature flash sterilization (UHT sterilization) in which heat treatment is performed at 120 to 150 ° C. for 2 to 3 seconds, high temperature short time sterilization (HTST sterilization) in which heat treatment is performed continuously at 72 ° C. or higher, for example, 72 to 75 ° C. for 15 seconds or more, high temperature holding sterilization (HTLT sterilization) in which heat treatment is performed at 75 ° C. or higher for 15 minutes or more in a holding system, low temperature holding sterilization (LTLT sterilization) in which heat treatment is performed at 63 to 65 ° C. for 30 minutes in a holding system, continuous low temperature sterilization (LTLT sterilization) in which heat treatment is performed continuously at 65 to 68 ° C. for 30 minutes or more, and ultra-high temperature sterilization (LL sterilization) in which heat treatment is performed at 135 to 150 ° C. for 1 to 4 seconds. In addition, the sterilization treatment is not limited to the above sterilization methods, as long as the thermal history represented by "heating temperature (product temperature) x heating time x pressure" is equal to or greater than that of the above-mentioned sterilization methods. For example, as employed in the experimental examples described below, a method of heat treating a milk fluid under normal pressure conditions until the product temperature reaches 95°C (at 95°C) can also be used. Note that normal pressure here means that the pressure inside the container is at normal pressure, and does not include pressure states where pressure is artificially increased or decreased.

[0026] (2) Lactic Acid Bacteria Treatment Step The lactic acid bacteria used in the lactic acid bacteria treatment step are not particularly limited, but include lactic acid bacteria commonly used in the production of fermented milk, such as Lactobacillus bulgaricus (L. bulgaricus), Streptococcus thermophilus (S. thermophilus), Lactobacillus casei (L. casei), Lactobacillus lactis (L. lactis), Lactobacillus gasseri (L. gasseri), Lactobacillus plantarum (L. plantarum), Lactobacillus acidophilus (L. acidophilus), and Bifidobacterium (Bifidobacterium). One type of lactic acid bacteria can be used alone, or two or more types can be used in combination.

[0027] In an embodiment in which one type of lactic acid bacteria is used alone, preferred are Lactobacillus bulgaricus, Lactobacillus thermophilus, and Lactobacillus casei, and more preferred are Lactobacillus bulgaricus 1589 (NITE BP-03716), Lactobacillus bulgaricus OLL 1073R-1 (FERM P-17227), Lactobacillus thermophilus 3078 (NITE BP-01697), and Lactobacillus casei P2203401. In an embodiment in which two or more types of lactic acid bacteria are used in combination, preferred is a combination of Lactobacillus bulgaricus and Lactobacillus thermophilus, more preferred are a combination of Lactobacillus bulgaricus 1589 and Lactobacillus thermophilus 3078, and a combination of Lactobacillus bulgaricus OLL 1073R-1 and Lactobacillus thermophilus 3078, and even more preferred is a combination of Lactobacillus bulgaricus 1589 and Lactobacillus thermophilus 3078. In addition, lactic acid bacteria isolated from fermented dairy products (e.g., Meiji Bulgaria Yogurt, Meiji Probio Yogurt LG 21, Meiji Probio Yogurt R-1, Meiji Bulgaria Yogurt dessert type, etc.) can also be used as a combination of Bulgarian bacteria and Thermophilic bacteria.

[0028] The amount of lactic acid bacteria added to the milk fluid is not particularly limited, but may be, for example, 10 ６ ~10８ cfu / ml, preferably 5 x 10 ６ ~10 ８ cfu / ml, more preferably 10 ７ ~10 ８ cfu / ml.

[0029] Lactic acid bacteria treatment of a milk fluid can be carried out by adding lactic acid bacteria to the milk fluid and then holding the milk fluid at a predetermined temperature, either statically or with stirring. The temperature of the lactic acid bacteria treatment is not particularly limited, as long as it can adjust the milk fluid (initial pH of about 7.0) to a final pH in the range of 5.2 to 6.5, as long as no curd is formed. The lower limit of the temperature for the lactic acid bacteria treatment is, for example, 30°C, preferably 32°C, more preferably 34°C, and even more preferably 36°C. The upper limit of the temperature for the lactic acid bacteria treatment is, for example, 45°C, preferably 44°C, and more preferably 43°C. The temperature range for the lactic acid bacteria treatment can be set by arbitrarily combining these lower and upper limits. Examples of the temperature range that can be selected include, but are not limited to, 30 to 45°C, 32 to 44°C, 34 to 43°C, and 36 to 43°C. Examples of methods for holding the milk fluid at rest include holding it in a jacketed tank or a thermostatic chamber. The method of stirring and maintaining the milk fluid may be any method or condition that can at least uniformly stir and mix the milk fluid, and examples include a method of stirring and mixing the milk fluid with stirring blades, and maintaining the milk fluid in a jacketed tank or a temperature-controlled room.

[0030] The duration of the lactic acid bacteria treatment is not particularly limited, as long as it is sufficient to adjust the final pH of the lactic acid bacteria treatment from a milky fluid (initial pH of approximately 7.0) to a range of 5.2 to 6.5, with no curd formation occurring. In other words, the lactic acid bacteria treatment can be terminated when the pH of the lactic acid bacteria-treated milky fluid reaches a range of 5.2 to 6.5 without forming curd. Although not limited, the lower limit of the lactic acid bacteria treatment time is, for example, 0.5 hours, preferably 1 hour, more preferably 1.5 hours, and even more preferably 2 hours. The upper limit of the lactic acid bacteria treatment time is, for example, 12 hours, preferably 10 hours, more preferably 9 hours, and even more preferably 8 hours. The duration of the lactic acid bacteria treatment can be set by arbitrarily combining these lower and upper limits. Although not limited, 0.5 to 12 hours, 1 to 10 hours, 1.5 to 9 hours, and 2 to 8 hours can be selected, for example.

[0031] The lactic acid bacteria treatment can be terminated by heat-treating the lactic acid bacteria-treated milk fluid to kill all or part of the lactic acid bacteria contained in the milk fluid or to reduce the activity of all or part of the lactic acid bacteria. The method and conditions for this heat treatment are not particularly limited as long as the above-mentioned object can be achieved and the effects of the present invention are not impaired. For example, a method of heat-treating the milk fluid until the temperature reaches 60°C (at 60°C) can be used.

[0032] The pH at the end of the lactic acid bacteria treatment can be set as follows, depending on the components of the milk fluid actually used. (a) In the case of a milk fluid that does not contain casein but contains whey protein as a milk-derived protein: pH at the end of the lactic acid bacteria treatment: 5.2 to 6.5, preferably 5.6 to 6.5, more preferably 5.8 to 6.5, even more preferably 6.0 to 6.5, and particularly preferably 6.0 to 6.4. When the pH at the end of the lactic acid bacteria treatment is 5.8 or higher, preferably 6.0 or higher, the resulting lactic acid bacteria-treated milk fluid does not taste sour and has a better flavor. Here, the milk fluid includes, for example, WPC and WPI. (b) In the case of a milk fluid that contains casein, or casein and whey protein as a milk-derived protein: pH at the end of the lactic acid bacteria treatment: 6.0 to 6.5, preferably 6.0 to 6.4, or 6.1 to 6.5, more preferably 6.1 to 6.4. If the pH after the lactic acid bacteria treatment is 6.0 or higher, the resulting lactic acid bacteria-treated milk fluid will not taste sour and will have a better flavor. Examples of the milk fluid include MPC, MPI, and MCC.

[0033] By adjusting the pH range at the end of the lactic acid bacteria treatment as described above depending on the components of the milk fluid, one of the effects of the present invention is to obtain a high-protein milk raw material with a suppressed milk-derived protein odor and a good flavor. Among these high-protein milk raw materials, a high-protein milk raw material with a pH of 6.0 or higher is also characterized by its low sourness (sourness). Therefore, when obtaining a high-protein milk raw material with a suppressed milk-derived protein odor and a reduced sourness, it is preferable to set the pH at the end of the lactic acid bacteria treatment to 6.0 or higher. Note that the method and equipment for lactic acid bacteria treatment of the milk fluid can be known methods and equipment used in the fermentation treatment of raw milk. For example, the lactic acid bacteria treatment can be performed using known methods and equipment used in the production of fermented milk products such as yogurt.

[0034] The lactic acid bacteria-treated milk fluid thus prepared can be subjected to a concentration step and / or a drying step, if necessary, to prepare it into a semi-solid or solid form.

[0035] The concentration step is not particularly limited, and includes, for example, a method in which the lactic acid bacteria-treated milk fluid is subjected to a dehydration (+desalting) process such as vacuum evaporation, reverse osmosis (RO) membrane treatment, or nanofiltration (NF) membrane treatment to obtain a semi-solid lactic acid bacteria-treated milk fluid having a total solids content of 20 to 50% by mass. The lactic acid bacteria-treated milk fluid obtained in the concentration step may be in a liquid or gel state. The total solids content in 100% by mass of the lactic acid bacteria-treated milk fluid is, for example, 20 to 50% by mass, preferably 20 to 40% by mass, more preferably 20 to 35% by mass, and even more preferably 20 to 30% by mass.

[0036] The drying step is not particularly limited, and includes, for example, a method in which the lactic acid bacteria-treated milk fluid or the semi-solid lactic acid bacteria-treated milk fluid after the concentration step is subjected to a dehydration treatment such as spray drying, freeze drying, drum drying, or the like to obtain a dried (solid) lactic acid bacteria-treated milk fluid having a water content of 2 to 5% by mass. The dried lactic acid bacteria-treated milk fluid obtained in the drying step may be in the form of a powder or granules, or may be in the form of granules obtained by sieving or granulating these, or may be in the form of tablets obtained by tableting (compression molding) these.

[0037] (II) Lactic Acid Bacteria-Treated High-Protein Milk Raw Material The lactic acid bacteria-treated high-protein milk raw material of the present invention is a liquid high-protein milk raw material having a milk-derived protein content of 50 parts by mass or more per 100 parts by mass of total solids, and is characterized by containing at least killed lactic acid bacteria, diacetyl, and 3-hydroxy-2-butanone, and having a pH in the range of 5.2 to 6.5. Preferably, the high-protein milk raw material is prepared (produced) by the production method described above.

[0038] As described above, the content of milk-derived protein per 100 parts by mass of total solids contained in the lactic acid bacteria-treated high-protein milk raw material may be 50 parts by mass or more, but is preferably 60 parts by mass or more, more preferably 70 parts by mass or more, even more preferably 75 parts by mass or more, and particularly preferably 80 parts by mass or more. There is no upper limit, but an example of the upper limit is 95 parts by mass.

[0039] The pH of the lactic acid bacteria-treated high-protein milk raw material can be set as follows, depending on the components of the lactic acid bacteria-treated high-protein milk raw material. (a) In the case of a lactic acid bacteria-treated high-protein milk raw material that does not contain casein but contains whey protein as a milk-derived protein: pH: 5.2 to 6.5, preferably 5.6 to 6.5, more preferably 5.8 to 6.5, even more preferably 6.0 to 6.5, and particularly preferably 6.0 to 6.4. When the pH is 5.8 or higher, preferably 6.0 or higher, the lactic acid bacteria-treated milk fluid does not taste sour and has a better flavor. Examples of the lactic acid bacteria-treated high-protein milk raw material include WPC and WPI. (b) In the case of a lactic acid bacteria-treated high-protein milk raw material that contains casein, or casein and whey protein as a milk-derived protein: pH: 6.0 to 6.5, preferably 6.0 to 6.4, or 6.1 to 6.5, more preferably 6.1 to 6.4. When the pH is 6.0 or higher, the lactic acid bacteria-treated high-protein milk raw material does not have a sour taste and has a better flavor. Here, examples of the lactic acid bacteria-treated high-protein milk raw material include MPC, MPI, and MCC.

[0040] In other words, as mentioned above, among these lactic acid bacteria-treated high-protein milk raw materials, lactic acid bacteria-treated high-protein milk raw materials with a pH of 6.0 or higher are characterized by having a suppressed milk-derived protein odor and a suppressed sourness.

[0041] Diacetyl and 3-hydroxy-2-butanone (hereinafter referred to as "acetoin") are aroma components (indicators of fermentation aroma) produced, for example, when milk components are fermented with lactic acid bacteria. As shown in the experimental examples described below, an increase in these aroma components was observed when milk fluid was treated with lactic acid bacteria. It is believed that the increase in these aroma components results in a suppression of milk-derived protein odor in the lactic acid bacteria-treated high-protein milk raw material of the present invention, resulting in a more favorable flavor, compared to high-protein milk raw materials not treated with lactic acid bacteria. The proportion of diacetyl contained in the lactic acid bacteria-treated high-protein milk raw material is not particularly limited, but can be 0.00001 to 0.001% by mass (0.1 to 10 ppm), preferably 0.00002 to 0.001% by mass (0.2 to 10 ppm), per 100% by mass of the total solids of the lactic acid bacteria-treated high-protein milk raw material. The proportion of acetoin contained in the lactic acid bacteria-treated high-protein milk raw material is not particularly limited, but may be 0.00001 to 0.01% by mass (0.1 to 100 ppm), preferably 0.00002 to 0.01% by mass (0.2 to 100 ppm), per 100% by mass of the total solids of the lactic acid bacteria-treated high-protein milk raw material. This aroma component can be analyzed based on the methods and procedures described in the Experimental Examples below.

[0042] The proportion of diacetyl contained in a liquid lactic acid bacteria-treated high-protein milk raw material is not particularly limited, but is, for example, 1 or more, preferably greater than 1, more preferably 1.5 or more, even more preferably 1.5 to 10, even more preferably 1.5 to 9, and even more preferably 1.5 to 8, compared to the proportion of diacetyl contained in a high-protein milk raw material produced with the same formulation and production method as the liquid lactic acid bacteria-treated high-protein milk raw material except for the absence of lactic acid bacteria treatment (defined as "1"). The proportion of diacetyl contained in a solid lactic acid bacteria-treated high-protein milk raw material is not particularly limited, but is, for example, 1 or more, preferably greater than 1, more preferably 1.5 or more, even more preferably 1.5 to 10, even more preferably 1.5 to 9, and even more preferably 1.5 to 8, compared to the proportion of diacetyl contained in a high-protein milk raw material produced with the same formulation and production method as the solid lactic acid bacteria-treated high-protein milk raw material except for the absence of lactic acid bacteria treatment (defined as "1"). Here, the "proportion of diacetyl contained in the high-protein milk raw material" can be determined from the chart (peak) area value corresponding to diacetyl in a headspace solid-phase microextraction method of gas chromatography-mass spectrometry, as described in the experimental examples below (the same applies to acetoin, dimethyl disulfide, dimethyl trisulfide, nonanal, and δ-decalactone below).

[0043] The proportion of acetoin contained in the liquid lactic acid bacteria-treated high-protein milk raw material is not particularly limited, but is, for example, 1 or more, preferably greater than 1, more preferably 1.5 or more, even more preferably 1.5 to 1000, even more preferably 1.5 to 900, and even more preferably 1.5 to 850, compared to the proportion of acetoin contained in the liquid lactic acid bacteria-treated high-protein milk raw material produced by the same formulation and production method as the liquid lactic acid bacteria-treated high-protein milk raw material, except that it is not treated with lactic acid bacteria. The proportion of acetoin contained in the solid lactic acid bacteria-treated high-protein milk raw material is, for example, 1 or more, preferably greater than 1, more preferably 1.5 or more, even more preferably 1.5 to 1000, even more preferably 1.5 to 900, and even more preferably 1.5 to 850, compared to the proportion of acetoin contained in the solid lactic acid bacteria-treated high-protein milk raw material produced by the same formulation and production method as the solid lactic acid bacteria-treated high-protein milk raw material.

[0044] Dimethyl disulfide (DMDS) and dimethyl trisulfide (DMTS) are aroma components (indicators of protein degradation) that are produced, for example, when protein-containing milk components are heat-treated, and nonanal is an aroma component (indicator of lipid degradation) that is produced, for example, when lipid-containing milk components are heat-treated. As shown in the experimental examples described below, a reduction in these aroma components was observed when milk fluid was treated with lactic acid bacteria. Due to the reduction in these aroma components, or the reduction in these components combined with the increase in diacetyl and acetoin, the milk-derived protein odor is suppressed in the lactic acid bacteria-treated high-protein milk raw material of the present invention compared to the high-protein milk raw material not treated with lactic acid bacteria. Furthermore, unpleasant flavors are suppressed, resulting in a good flavor and a refreshing aftertaste.

[0045] The proportion of DMDS contained in the lactic acid bacteria-treated high-protein milk raw material is not particularly limited, but can be 0.00000001 to 0.0000005% by mass (0.1 to 5 ppb), preferably 0.00000001 to 0.0000004% by mass (0.1 to 4 ppb), per 100% by mass of the total solids of the lactic acid bacteria-treated high-protein milk raw material. The proportion of DMTS contained in the lactic acid bacteria-treated high-protein milk raw material is also not particularly limited, but can be 0.000000004 to 0.0000005% by mass (0.04 to 5 ppb), preferably 0.000000004 to 0.0000004% by mass (0.04 to 4 ppb), per 100% by mass of the total solids of the lactic acid bacteria-treated high-protein milk raw material. Furthermore, the proportion of nonanal contained in the lactic acid bacteria-treated high-protein milk raw material is not particularly limited, but can be 0.00000001 to 0.000001% by mass (0.1 to 10 ppb), preferably 0.00000001 to 0.0000009% by mass (0.1 to 9 ppb), per 100% by mass of the total solids content of the lactic acid bacteria-treated high-protein milk raw material. This aroma component can be analyzed based on the methods and procedures described in the Experimental Examples below.

[0046] The proportion of DMDS contained in the liquid lactic acid bacteria-treated high-protein milk raw material is not particularly limited, but is, for example, 1 or less, preferably less than 1, more preferably 0.9 or less, even more preferably 0.2 to 0.9, even more preferably 0.3 to 0.9, and even more preferably 0.3 to 0.8, compared to the proportion of DMDS contained in a high-protein milk raw material produced with the same formulation and production method as the liquid lactic acid bacteria-treated high-protein milk raw material, except that no lactic acid bacteria treatment is performed. The proportion of DMDS contained in the solid lactic acid bacteria-treated high-protein milk raw material is not particularly limited, but is, for example, 1 or less, preferably less than 1, more preferably 0.9 or less, even more preferably 0.2 to 0.9, even more preferably 0.3 to 0.9, and even more preferably 0.3 to 0.8, compared to the proportion of DMDS contained in a high-protein milk raw material produced with the same formulation and production method as the solid lactic acid bacteria-treated high-protein milk raw material, except that no lactic acid bacteria treatment is performed.

[0047] The proportion of DMTS contained in the liquid lactic acid bacteria-treated high-protein milk raw material is not particularly limited, but is, for example, 1 or less, preferably less than 1, more preferably 0.9 or less, even more preferably 0.2 to 0.9, even more preferably 0.3 to 0.9, and even more preferably 0.3 to 0.8, compared to the proportion (defined as "1") of DMTS contained in a high-protein milk raw material produced with the same formulation and production method as the liquid lactic acid bacteria-treated high-protein milk raw material, except that no lactic acid bacteria treatment is performed. The proportion of DMTS contained in the solid lactic acid bacteria-treated high-protein milk raw material is not particularly limited, but is, for example, 1 or less, preferably less than 1, more preferably 0.9 or less, even more preferably 0.2 to 0.9, even more preferably 0.3 to 0.9, and even more preferably 0.3 to 0.8, compared to the proportion (defined as "1") of DMTS contained in a high-protein milk raw material produced with the same formulation and production method as the solid lactic acid bacteria-treated high-protein milk raw material, except that no lactic acid bacteria treatment is performed.

[0048] The proportion of nonanal contained in the liquid lactic acid bacteria-treated high-protein milk raw material is not particularly limited, but is, for example, 1 or less, preferably less than 1, more preferably 0.9 or less, even more preferably 0.1 to 0.9, even more preferably 0.2 to 0.9, and even more preferably 0.3 to 0.9, compared to the proportion of nonanal contained in a high-protein milk raw material produced with the same formulation and production method as the liquid lactic acid bacteria-treated high-protein milk raw material except for the absence of lactic acid bacteria treatment (defined as "1"). The proportion of nonanal contained in the solid lactic acid bacteria-treated high-protein milk raw material is not particularly limited, but is, for example, 1 or less, preferably less than 1, more preferably 0.9 or less, even more preferably 0.1 to 0.9, even more preferably 0.2 to 0.9, and even more preferably 0.3 to 0.9, compared to the proportion of nonanal contained in a high-protein milk raw material produced with the same formulation and production method as the solid lactic acid bacteria-treated high-protein milk raw material except for the absence of lactic acid bacteria treatment (defined as "1").

[0049] δ-Decalactone is an indicator of milk flavor. As shown in the experimental examples described below, δ-decalactone hardly changed even when milk fluid was treated with lactic acid bacteria. In other words, lactic acid bacteria-treated high-protein milk raw materials contain the same amount of δ-decalactone as high-protein milk raw materials not treated with lactic acid bacteria. This indicates that lactic acid bacteria-treated high-protein milk raw materials have the same milk flavor as high-protein milk raw materials not treated with lactic acid bacteria. In other words, it can be said that lactic acid bacteria treatment does not significantly impair the milk flavor. The proportion of δ-decalactone contained in the lactic acid bacteria-treated high-protein milk raw material is not particularly limited, but can be 0.00000001 to 0.0000005% (0.1 to 5 ppb), preferably 0.00000002 to 0.0000005% (0.2 to 5 ppb), per 100% by mass of the total solids of the lactic acid bacteria-treated high-protein milk raw material. These aroma components can be analyzed according to the methods and procedures described in the experimental examples below.

[0050] The proportion of δ-decalactone contained in the liquid lactic acid bacteria-treated high-protein milk raw material is not particularly limited, but is, for example, 0.7 to 1.3, preferably 0.7 to 1.2, more preferably 0.8 to 1.2, even more preferably 0.8 to 1.1, even more preferably 0.9 to 1.1, and even more preferably 0.9 to 1, compared to the proportion of δ-decalactone (defined as "1") contained in a high-protein milk raw material produced with the same formulation and production method as the liquid lactic acid bacteria-treated high-protein milk raw material except that it is not treated with lactic acid bacteria. The proportion of δ-decalactone contained in the solid lactic acid bacteria-treated high-protein milk raw material is not particularly limited, but is, for example, 0.7 to 1.3, preferably 0.7 to 1.2, more preferably 0.8 to 1.2, even more preferably 0.8 to 1.1, even more preferably 0.9 to 1.1, and even more preferably 0.9 to 1, compared to the proportion of δ-decalactone (defined as "1") contained in a high-protein milk raw material produced with the same formulation and production method as the solid lactic acid bacteria-treated high-protein milk raw material except that it is not treated with lactic acid bacteria.

[0051] The lactic acid bacteria-treated high-protein milk raw material of the present invention is not particularly limited, but includes those containing free amino acids at the following concentrations per kg of total solids of the lactic acid bacteria-treated high-protein milk raw material. (a) In the case of a lactic acid bacteria-treated high-protein milk raw material (specifically, WPC or WPI) that does not contain casein but contains whey protein as the milk-derived protein: Histidine (His): for example, 30 μmol / kg or more, preferably 30 to 1000 μmol / kg, more preferably 40 to 900 μmol / kg, and even more preferably 50 to 800 μmol / kg Asparagine (Asn): for example, 10 μmol / kg or more, preferably 10 to 300 μmol / kg, more preferably 10 to 250 μmol / kg, and even more preferably 15 to 200 μmol / kg Serine (Ser): For example, 30 μmol / kg or more, preferably 30 to 2500 μmol / kg, more preferably 40 to 2000 μmol / kg, and even more preferably 50 to 1500 μmol / kg. Glutamine (Gln): For example, 10 μmol / kg or more, preferably 10 to 300 μmol / kg, more preferably 10 to 250 μmol / kg, and even more preferably 15 to 200 μmol / kg. Glycine (Gly): For example, 100 μmol / kg or more, preferably 100 to 2500 μmol / kg, more preferably 100 to 2000 μmol / kg, and even more preferably 100 to 1500 μmol / kg. Aspartic acid (Asp): for example, 30 μmol / kg or more, preferably 30 to 1000 μmol / kg, more preferably 40 to 900 μmol / kg, and even more preferably 50 to 800 μmol / kg. Threonine (Thr): for example, 20 μmol / kg or more, preferably 20 to 1000 μmol / kg, more preferably 30 to 900 μmol / kg, and even more preferably 30 to 800 μmol / kg. Alanine (Ala): for example, 80 μmol / kg or more, preferably 80 to 2000 μmol / kg, more preferably 100 to 1500 μmol / kg, and even more preferably 100 to 1000 μmol / kg.Proline (Pro): For example, 100 μmol / kg or more, preferably 100 to 2500 μmol / kg, more preferably 200 to 2500 μmol / kg, and even more preferably 200 to 2000 μmol / kg. Lysine (Lys): For example, 200 μmol / kg or more, preferably 200 to 2500 μmol / kg, more preferably 300 to 2000 μmol / kg, and even more preferably 300 to 1500 μmol / kg. Methionine (Met): For example, 10 μmol / kg or more, preferably 10 to 1000 μmol / kg, more preferably 10 to 800 μmol / kg, and even more preferably 15 to 600 μmol / kg. Isoleucine (Ile): For example, 10 μmol / kg or more, preferably 10 to 1000 μmol / kg, more preferably 10 to 800 μmol / kg, and even more preferably 15 to 600 μmol / kg. Valine (Val): For example, 30 μmol / kg or more, preferably 30 to 3000 μmol / kg, more preferably 40 to 2500 μmol / kg, and even more preferably 50 to 2000 μmol / kg. Leucine (Leu): For example, 30 μmol / kg or more, preferably 30 to 1500 μmol / kg, more preferably 50 to 1200 μmol / kg, and even more preferably 80 to 1000 μmol / kg.

[0052] (b) In the case of lactic acid bacteria-treated high-protein milk raw materials (specifically, MPC, MPI, and MCC) containing casein or casein and whey protein as the milk-derived protein: Histidine (His): for example, 30 μmol / kg or more, preferably 30 to 1000 μmol / kg, more preferably 40 to 900 μmol / kg, and even more preferably 50 to 800 μmol / kg Asparagine (Asn): for example, 10 μmol / kg or more, preferably 10 to 300 μmol / kg, more preferably 10 to 250 μmol / kg, and even more preferably 15 to 200 μmol / kg Glutamine (Gln): for example, 10 μmol / kg or more, preferably 10 to 2000 μmol / kg, more preferably 30 to 1500 μmol / kg, and even more preferably 50 to 1000 μmol / kg Glycine (Gly): For example, 100 μmol / kg or more, preferably 100 to 2000 μmol / kg, more preferably 150 to 1500 μmol / kg, and even more preferably 150 to 1000 μmol / kg. Arginine (Arg): For example, 50 μmol / kg or more, preferably 50 to 2000 μmol / kg, more preferably 60 to 1700 μmol / kg, and even more preferably 80 to 1500 μmol / kg. Aspartic acid (Asp): For example, 40 μmol / kg or more, preferably 40 to 1000 μmol / kg, more preferably 50 to 900 μmol / kg, and even more preferably 60 to 800 μmol / kg. Threonine (Thr): For example, 20 μmol / kg or more, preferably 20 to 600 μmol / kg, more preferably 30 to 500 μmol / kg, and even more preferably 30 to 400 μmol / kg. Alanine (Ala): For example, 50 μmol / kg or more, preferably 50 to 2000 μmol / kg, more preferably 70 to 1700 μmol / kg, and even more preferably 100 to 1500 μmol / kg. Proline (Pro): For example, 60 μmol / kg or more, preferably 60 to 2500 μmol / kg, more preferably 100 to 2000 μmol / kg, and even more preferably 150 to 2000 μmol / kg.Lysine (Lys): For example, 50 μmol / kg or more, preferably 50 to 2000 μmol / kg, more preferably 70 to 1700 μmol / kg, and even more preferably 100 to 1500 μmol / kg. Tyrosine (Tyr): For example, 20 μmol / kg or more, preferably 20 to 2000 μmol / kg, more preferably 25 to 1500 μmol / kg, and even more preferably 30 to 1000 μmol / kg. Methionine (Met): For example, 5 μmol / kg or more, preferably 5 to 600 μmol / kg, more preferably 10 to 500 μmol / kg, and even more preferably 15 to 400 μmol / kg. Isoleucine (Ile): For example, 20 μmol / kg or more, preferably 20 to 1000 μmol / kg, more preferably 25 to 800 μmol / kg, and even more preferably 30 to 600 μmol / kg. Valine (Val): For example, 20 μmol / kg or more, preferably 20 to 2500 μmol / kg, more preferably 50 to 2000 μmol / kg, and even more preferably 80 to 1500 μmol / kg. Leucine (Leu): For example, 20 μmol / kg or more, preferably 20 to 1500 μmol / kg, more preferably 50 to 1200 μmol / kg, and even more preferably 80 to 1000 μmol / kg. Phenylalanine (Phe): For example, 20 μmol / kg or more, preferably 20 to 1000 μmol / kg, more preferably 25 to 800 μmol / kg, and even more preferably 30 to 600 μmol / kg. These free amino acids can be analyzed using the methods and procedures described in the Experimental Examples below.

[0053] The lactic acid bacteria-treated high-protein milk raw material of the present invention includes a lactic acid bacteria-treated high-protein milk raw material prepared in a semi-solid or solid form by concentrating and / or drying the liquid lactic acid bacteria-treated high-protein milk raw material described above. The concentration process is not particularly limited, and includes, for example, a method in which a lactic acid bacteria-treated milk fluid is subjected to a dehydration (plus desalination) process such as vacuum evaporation, reverse osmosis (RO) membrane treatment, or nanofiltration (NF) membrane treatment to obtain a semi-solid lactic acid bacteria-treated milk fluid having a total solids content of 20 to 50% by mass. The lactic acid bacteria-treated milk fluid obtained in the concentration step may be in a liquid or semi-solid (gel-like) state. The total solids content is preferably 20 to 40% by mass, more preferably 20 to 35% by mass, and even more preferably 20 to 30% by mass. The drying process is not particularly limited, and includes, for example, a method in which the lactic acid bacteria-treated milk fluid or the semi-solid lactic acid bacteria-treated milk fluid obtained in the concentration step is subjected to a dehydration process such as spray drying, freeze drying, or drum drying to obtain a dried product of a solid lactic acid bacteria-treated milk fluid having a water content of 2 to 5% by mass. The dried product of the lactic acid bacteria-treated milk fluid obtained in the drying step may be in the form of a powder or granules, or may be in the form of granules obtained by sieving or granulating these, or may be in the form of tablets obtained by tableting (compression molding) these.

[0054] (III) Foods and Drinks, and Their Manufacturing Methods According to one aspect of the present invention, there is provided a method for manufacturing a food or drink, comprising the step of incorporating a lactic acid bacteria-treated high-protein milk raw material produced by the manufacturing method of the present invention into a food or drink. In addition to the lactic acid bacteria-treated high-protein milk raw material produced by the manufacturing method of the present invention, optional ingredients can be blended (mixed) into the food or drink, as needed. Such optional ingredients include, but are not limited to, ingredients typically blended into foods and drinks, such as aqueous ingredients, oil-based ingredients, carbohydrates, dietary fiber, polysaccharides, proteins, peptides, amino acids, lipids, organic acids, various physiologically active substances, vitamins, minerals, acidulants, flavorings, sweeteners, emulsifiers, thickeners, gelling agents, functional ingredients, oils and fats, excipients, colorants, preservatives, and water (hot water, warm water, room temperature water, cold water).

[0055] According to a preferred embodiment of the present invention, there is provided a method for producing a food or beverage, which comprises the step of mixing one or more selected from the group consisting of aqueous raw materials, oil-based raw materials, flavorings, sweeteners, emulsifiers, thickeners, gelling agents, functional ingredients, oils and fats, excipients, and water with a lactic acid bacteria-treated high-protein milk raw material produced by the production method of the present invention, and incorporating the mixture into the food or beverage.

[0056] Examples of aqueous ingredients that can be contained in the food and beverage of the present invention include dairy ingredients other than the lactic acid bacteria-treated high-protein milk ingredient of the present invention (cow's milk, skim milk, low-fat milk, ingredient-adjusted milk, etc.), dairy drinks, fermented milk, soy milk, fruit juice, vegetable juice, fruit / vegetable paste, fruit / vegetable extract, alcoholic beverages, liquid sugar, etc. Examples of oil-based ingredients that can be contained in the food and beverage of the present invention include butter, margarine, shortening, cream, chocolate, cacao mass, cocoa butter, almond paste, etc.

[0057] The food and drink produced by the production method of the present invention may be in any form, such as a solution, suspension, emulsion, powder, paste, semi-solid product, or solid product, as long as it is orally ingestible. Examples of such food and drink products include, but are not limited to, instant foods such as instant noodles, retort pouch foods, canned foods, microwave foods, instant soups, miso soups, and freeze-dried foods; beverages such as soft drinks, fruit juice drinks, vegetable drinks, soy milk drinks, coffee drinks, tea drinks, powdered drinks, concentrated drinks, and alcoholic beverages; flour products such as bread, pasta, noodles, cake mix, and breadcrumbs; candy, caramel, gummy candy, chewing gum, chocolate, cookies, biscuits, bars, cakes, pies, snacks, crackers, Japanese sweets, and puddings. Examples of such foods include confectioneries such as jelly, mousse, desserts, and ice cream; condiments such as sauces, processed tomato seasonings, flavor seasonings, cooking mixes, sauces, dressings, soups, and curry and stew bases; processed oils and fats such as butter, margarine, and mayonnaise; dairy products such as milk drinks, fermented milk, lactic acid bacteria drinks, ice creams (ice cream, ice milk, lacto ice cream), and creams; processed agricultural products such as canned agricultural products, jams, marmalades, and cereals; frozen foods, and liquid foods. Food and drink products also include health foods, functional foods (including, for example, foods for specified health uses, foods with nutrient functions, or foods with functional claims), nutritional supplements, foods for special dietary uses (including, for example, foods for patients, infant formula, powdered milk for pregnant and nursing women, and foods for people with difficulty swallowing), and liquid infant formula (also known as liquid infant milk). Among these, beverages, confectionery, dairy products, and liquid foods are preferred, and fermented milk, milk drinks, coffee drinks, tea drinks, soft drinks, powdered drinks, liquid foods, ice creams (ice cream, ice milk, lacto ice cream), frozen desserts, and pudding are more preferred.

[0058] The food and beverage products of the present invention can be produced by any method as long as it includes a step of blending the lactic acid bacteria-treated high-protein milk raw material of the present invention. For example, they can be produced according to conventional methods depending on the product.

[0059] The lactic acid bacteria-treated high-protein milk raw material to be incorporated into the food or beverage of the present invention has a reduced milk-derived protein odor, and therefore can enhance the protein content of the food or beverage without impairing the original flavor of the food or beverage and while maintaining a favorable flavor. Therefore, the present invention can provide a method for producing a food or beverage that contains milk-derived protein but has a reduced milk-derived protein odor.

[0060] Here, "reduced milk-derived protein odor" means that the protein odor derived from the high-protein milk raw material is reduced. Specifically, this means that when the lactic acid bacteria-treated high-protein milk raw material of the present invention is used as the high-protein milk raw material, the milk-derived protein odor is reduced compared to when a high-protein milk raw material not treated with lactic acid bacteria is used. Here, the protein odor refers to the protein odor (retronasal) sensed in the oral cavity and nasal cavity. More objectively, the reduction of the milk-derived protein odor can also be evaluated by the reduction of DMDS and / or DMTS, which are indicators of protein deterioration, when the lactic acid bacteria-treated high-protein milk raw material of the present invention is used as the high-protein milk raw material, compared to when a high-protein milk raw material not treated with lactic acid bacteria is used. More objectively, the reduction of the milk-derived protein odor can be evaluated by the reduction of DMDS and / or DMTS and the increase of diacetyl and / or acetoin, which are indicators of fermented aroma, when the lactic acid bacteria-treated high-protein milk raw material of the present invention is used as the high-protein milk raw material, compared to when a high-protein milk raw material not treated with lactic acid bacteria is used.

[0061] Therefore, the food and beverage obtained by the production method of the present invention is characterized by a reduced protein odor derived from the high-protein milk raw material blended as a dairy raw material. In other words, according to an aspect of the present invention, by using a lactic acid bacteria-treated high-protein milk raw material as the high-protein milk raw material, a food and beverage is provided in which the protein odor derived from the high-protein milk raw material is reduced compared to when a high-protein milk raw material not treated with lactic acid bacteria is used. Furthermore, according to a preferred aspect of the present invention, by using a lactic acid bacteria-treated high-protein milk raw material as the high-protein milk raw material, a food and beverage is provided in which the off-flavor is reduced and the refreshing feeling is improved compared to when a high-protein milk raw material not treated with lactic acid bacteria is used. It is thought that such a flavor improvement effect is obtained, for example, by reducing the protein odor derived from the high-protein milk raw material blended as a dairy raw material.

[0062] (IV) Method for Improving the Flavor of High-Protein Milk Raw Materials The present invention is a method for improving the flavor of high-protein milk raw materials, comprising the following steps: (1) preparing a milk fluid from the milk raw material, the milk fluid having a total solid content of 5 to 15 mass % and a milk-derived protein content of 50 mass parts or more per 100 mass parts of total solid content; and (2) adding lactic acid bacteria to the milk fluid and maintaining the pH until it reaches 5.2 to 6.5, thereby obtaining a lactic acid bacteria-treated milk fluid within the pH range.

[0063] These steps (1) and (2) are as explained in (I) above, and the descriptions thereof are incorporated herein by reference. Furthermore, as explained in (I), the lactic acid bacteria-treated milk fluid may be sterilized after step (1), and similarly, the lactic acid bacteria-treated milk fluid may be concentrated and / or dried after step (2).

[0064] "Improvement of flavor" includes at least the meaning of "reduction of milk-derived protein odor." "Reduction of milk-derived protein odor" means that the protein odor derived from the high-protein milk raw material is reduced. Specifically, by using the lactic acid bacteria-treated high-protein milk raw material obtained in steps (1) and (2) as the high-protein milk raw material, the protein odor is reduced compared to when a high-protein milk raw material not treated with lactic acid bacteria is used. Here, the protein odor refers to the protein odor (retronasal) sensed from the oral cavity to the nasal cavity. More objectively, the reduction of milk-derived protein odor can also be evaluated by the reduction of DMDS and / or DMTS, which are indicators of protein deterioration, by using the lactic acid bacteria-treated high-protein milk raw material of the present invention as the high-protein milk raw material compared to when a high-protein milk raw material not treated with lactic acid bacteria is used. More objectively, by using the lactic acid bacteria-treated high-protein milk raw material of the present invention as the high-protein milk raw material, the amount of DMDS and / or DMTS is reduced compared to when a high-protein milk raw material that has not been treated with lactic acid bacteria is used, and the amount of diacetyl and / or acetoin, which are indicators of fermented aroma, is increased, so that the reduction in milk-derived protein odor can also be evaluated.

[0065] "Improved flavor" preferably further includes the meaning of "refreshing aftertaste." "Refreshing aftertaste" also means that the off-flavors derived from the high-protein milk raw material are reduced. Specifically, it means that by using the lactic acid bacteria-treated high-protein milk raw material obtained in steps (1) and (2) as the high-protein milk raw material, the aftertaste is refreshed compared to when a high-protein milk raw material that has not been treated with lactic acid bacteria is used. More objectively, by using the lactic acid bacteria-treated high-protein milk raw material of the present invention as the high-protein milk raw material, the amount of DMDS and / or DMTS is reduced and diacetyl and / or acetoin is increased compared to when a high-protein milk raw material that has not been treated with lactic acid bacteria is used, and this can also be used to evaluate the refreshing aftertaste.

[0066] As described above, in this specification, the terms "comprise" and "contain" encompass the meanings of "consist of" and "consist essentially of."

[0067] The present invention will be described below using experimental examples to aid in understanding the configuration and effects of the present invention. However, the present invention is not limited by these experimental examples. Unless otherwise specified, the following experiments were carried out at room temperature (25±5°C) and atmospheric pressure (normal pressure). Unless otherwise specified, "%" and "parts" in the following descriptions mean "% by mass" and "parts by mass," respectively.

[0068] The raw materials and lactic acid bacteria used in the experimental examples (Examples and Comparative Examples) described below are as follows: (Raw Materials) Milk protein concentrate (MPC): MPC4850 (casein 64%, whey 16%), powder, Fonterra Whey protein concentrate (WPC): WPC392 (whey 80%), powder, Fonterra

[0069] (Lactic acid bacteria) (a) Lactobacillus delbrueckii subsp. bulgaricus 1589 (NITE BP-03716) (hereinafter referred to as "Lactobacillus delbrueckii subsp. bulgaricus 1589"). Lactobacillus delbrueckii subsp. bulgaricus 1589 was internationally deposited on August 9, 2022, with the Patent Microorganisms Depositary of the National Institute of Technology and Evaluation, located at Room 122, 2-5-8 Kazusa Kamatari, Kisarazu City, Chiba Prefecture, Japan, under the identification mark "Lactobacillus delbrueckii subsp. Bulgaricus 1589" (accession number: NITE BP-03716). (b) Lactobacillus bulgaricus OLL 1073R-1 (FERM BP-10741) (hereinafter referred to as "Lactobacillus bulgaricus OLL 1073R-1") (high EPS (exopolysaccharide)-producing strain) Lactobacillus bulgaricus OLL 1073R-1 was internationally deposited on February 22, 1999 (domestic deposit date) with the International Patent Organism Depositary of the National Institute of Advanced Industrial Science and Technology, located at Central 6, 1-1-1 Higashi, Tsukuba City, Ibaraki Prefecture, Japan, under the identification designation "Lactobacillus delbrueckii subsp. Bulgaricus OLL 1073R-1" (accession number: FERM BP-10741). The National Institute of Advanced Industrial Science and Technology (AIST) Patent Organism Depositary was merged with the National Institute of Technology and Evaluation (NITE) Patent Microorganism Depositary in April 2012, and its microbial deposit operations are now being carried out by the National Institute of Technology and Evaluation Patent Organism Depositary (NITE-IPOD) (Room 120, 2-5-8 Kazusa Kamatari, Kisarazu City, Chiba Prefecture, 292-0818, Japan). (c) Streptococcus thermophilus 3078 (NITE BP-01697) (hereinafter referred to as "Thermophilus strain 3078"). The Thermophilus strain 3078 was internationally deposited with the Patent Microorganism Depositary on August 23, 2013, under the identification designation "Streptococcus thermophilus OLS3078" (Accession number: NITE BP-01697).(d) Lactobacillus casei P2203401 (hereinafter referred to as "Lactobacillus casei P2203401").

[0070] In the experimental examples described below, aroma compounds and free amino acids were analyzed according to the following method. (Analysis of Aroma Compounds) (a) Analysis Method: Headspace Solid Phase Microextraction (HS-SPME) with Gas Chromatography-Mass Spectrometry (GC / MS) (b) Preparation of Analytical Sample: If the sample is liquid, place 3 mL of the liquid sample and 5 mL of saturated saline in a 20 mL vial and mix. If the sample is powder, place 0.3 g of the powder sample and 8 mL of saturated saline in a 20 mL vial and mix.

[0071] (c) Analytical operating conditions: SPME fiber: DVB / CAR / PDMS (Merck), film thickness 50 / 30 μm, extraction temperature and time: 60°C, 40 minutes, GC / MS equipment: 7890GC / 5977AMS (Agilent Technologies), injection port temperature and mode: 250°C, split injection 1:5, carrier gas: helium, 1 mL / min, column: DB-WAX-UI, 0.25 mm x 30 m, film thickness 0.25 μm, oven: 40°C, 5 minutes → 15°C / min → 250°C, 10 minutes, ion source temperature: 230°C, scan range: m / z 33-200

[0072] (Analysis of free amino acids) (a) Analysis method: Ultra Performance Liquid Chromatography / Mass Spectrometry (UPLC / MS / MS) (b) Preparation of analytical sample: If the sample is in powder form: Prepare an aqueous solution (10% by mass) of the powdered sample.

[0073] (c) Analytical operating conditions: UPLC / MS / MS device: ACUITY UPLC-MSMS (TQD) (Waters), Column: ACCQ-TAGTMULTRA C18, 1.7 mm, 2.1 x 100 mm, Oven: 55°C, Sample injection volume: 10 μL, Solvent A: ACCQ TagUltra A diluted 20 times with ultrapure water. Solvent B: ACCQ TagUltra B used as is. Strong: 100% CAN, Weak, Seal: 10% CAN in MilliQ. UPLC operating conditions: Inlet Method Flow Rate: 0.7 mL / min. 0-2 min: 90% Diluent A, 2-10 min: 85% Diluent A, 10-12.5 min: 0% Diluent A, 12.5-16 min: 90% Diluent A. MS analytical conditions: MS Tune, MS Mode: MSMS (ESI+ mode), Capillary Voltage: 3.5 kV, Desolvation temperature: 350°C, Desolvation gas (N2): 800 L / h, Cone gas (N2): 250 L / h, Collision gas (Ar): 0.15 mL / min (9 mL / h). MS Monitor: Monitoring time 0-10 min: HMB(mz / mz); 117.1 > 59.0. , Cone Voltage 20V, , Collision energy 10 eV, dwell 0.2s HICA(mz / mz);131.1 > 85.0 , Cone Voltage 20V, , Collision energy 10 eV, dwell 0.4s 2H2MB(mz / mz);117.1 > 71.0 , Cone Voltage 20V, , Collision energy 10 eV, dwell 0.2s

[0074] In the experimental examples described below, sensory evaluations were conducted according to the following method. (Sensory Evaluation) (a) Expert Panel: Experienced individuals (sensory evaluation experts) who have received in-house sensory evaluation training and perform sensory evaluations on a daily basis. (b) Sensory Evaluation Test Each expert panelist placed test samples (lactic acid bacteria-treated sample [invention sample] and untreated sample [control sample]) adjusted to room temperature (25±5°C) in their mouths and swallowed them, and evaluated the protein odor (retronasal) perceived from the oral cavity to the nasal cavity, and the clean aftertaste (reduction of unpleasant flavors) perceived after swallowing. The inventive sample and the control sample were compared to evaluate the difference (strength) using a paired comparison method. Details of the inventive sample and the control sample are provided below.

[0075] In addition, when evaluating the protein odor and the cleanness of the aftertaste, each expert panel checked the flavor (protein odor and aftertaste) of the control sample in advance and discussed it with each other to unify the internal standards held by each expert panel.

[0076] Each expert panelist scored the protein odor and the clean aftertaste according to the following criteria, and the average score was calculated to give an overall evaluation. [Protein odor] 3: Reduced protein odor compared to the control sample 2: Same level of protein odor compared to the control sample 1: Increased protein odor compared to the control sample [Clean aftertaste] 3: No unpleasant aftertaste compared to the control sample, very clean 2: Same level of aftertaste (unclear) compared to the control sample 1: Unclear aftertaste compared to the control sample, less clean

[0077] Experimental Example 1. Production of a liquid lactic acid bacteria-treated high-protein milk raw material using MPC as a milk raw material and its evaluation (1) Production of a liquid lactic acid bacteria-treated high-protein milk raw material MPC was dissolved in warm water (60°C) to prepare an MPC liquid with a total solid content of 10% by mass (milk-derived protein content per 100 mass parts of total solids: 80 mass parts). This MPC liquid was heat sterilized (reaching 95°C) and then cooled (40°C) to prepare a heat-sterilized MPC liquid. A predetermined amount (10 6 ~10 8cfu / ml) and stirred at the temperature and for the time shown in Table 1 to prepare lactic acid bacteria-treated MPC liquids having the pH shown in Table 1. None of these lactic acid bacteria-treated MPC liquids formed curd and were in liquid form. Next, these lactic acid bacteria-treated MPC liquids were heated (up to 60°C) and then cooled (to 10°C or below) to produce liquid lactic acid bacteria-treated MPC (lactic acid bacteria-treated high-protein milk raw material). Hereinafter, these are referred to as "lactic acid bacteria-treated milk raw material" (invention samples 1-a to 1-f).

[0078]

[0079] (2) Analysis of Aroma Components of Liquid Lactic Acid Bacteria-Treated High-Protein Milk Raw Material Using the headspace solid-phase microextraction method of gas chromatography-mass spectrometry described above, the aroma components of the lactic acid bacteria-treated milk raw material (invention samples 1-a to 1-f) produced in Experimental Example 1(1) and the heat-sterilized MPC liquid (milk raw material not treated with lactic acid bacteria) (control sample) were analyzed. The aroma components selected were the sulfur compounds dimethyl disulfide (DMDS) and dimethyl trisulfide (DMTS) (both indicators of protein deterioration), nonanal (indicator of lipid deterioration), diacetyl (indicator of fermented aroma), acetoin (3-hydroxy-2-butanone) (indicator of fermented aroma), and δ-decalactone (indicator of milkiness).

[0080] The analytical value of the aroma components of the control sample (area value of the chart) was set to 1.0, and the analytical values ​​of the aroma components of the lactic acid bacteria-treated milk raw materials (invention samples 1-a to 1-f) were calculated as relative values. The results are shown in Table 2.

[0081]

[0082] As shown in Table 2, in the liquid lactic acid bacteria-treated milk raw materials (invention samples 1-a to 1-f), the protein degradation indicators DMDS and DMTS, and the lipid degradation indicator nonanal, tended to decrease compared to the liquid non-lactic acid bacteria-treated milk raw material (control sample). On the other hand, inventive samples 1-a to 1-f, the fermentation aroma indicators diacetyl and acetoin tended to increase compared to the control sample. Furthermore, inventive samples 1-a to 1-f, the δ-decalactone tended to remain almost unchanged compared to the control sample.

[0083] (3) Sensory evaluation of liquid lactic acid bacteria-treated high-protein milk raw material Five expert panelists evaluated the protein odor and clean aftertaste of the lactic acid bacteria-treated milk raw materials (invention samples 1-a to 1-f) produced in Experimental Example 1 (1) according to the methods described above. The average scores of the five expert panelists are shown in Table 3.

[0084]

[0085] As shown in Table 3, the liquid lactic acid bacteria-treated milk raw materials (invention samples 1-a to 1-f) all had a reduced protein odor and a clean aftertaste compared to the liquid milk raw material not treated with lactic acid bacteria (control sample). Furthermore, none of the inventive samples 1-a to 1-f had a sour taste.

[0086] Based on the results shown in Table 2, it can be inferred that the reduction in DMDS and DMTS, which are one of the causes of protein odor, and the increase in diacetyl and acetoin exerted a masking effect, thereby reducing the protein odor and providing a clean aftertaste.

[0087] Experimental Example 2. Production and evaluation of powdered lactic acid bacteria-treated high-protein milk raw material using MPC as a milk raw material (1) Production of powdered lactic acid bacteria-treated high-protein milk raw material Using a spray dryer (spray drying device), of the liquid lactic acid bacteria-treated MPC (lactic acid bacteria-treated high-protein milk raw material) produced in Experimental Example 1 (1), inventive samples 1-a and 1-b, and the heat-sterilized MPC liquid before lactic acid bacteria treatment (milk raw material not treated with lactic acid bacteria, control sample) were spray-dried (inlet air temperature: 180-185°C, exhaust air temperature: 80-85°C) to produce powdered (solid) lactic acid bacteria-treated MPC (lactic acid bacteria-treated high-protein milk raw material, inventive samples 2-a and 2-b) and powdered MPC not treated with lactic acid bacteria (control sample). Hereinafter, these are referred to as "powdered lactic acid bacteria-treated milk raw material" (invention samples 2-a and 2-b) and "powdered non-lactic acid bacteria-treated milk raw material" (control sample).

[0088] (2) Analysis of Aroma Components of Powdered Lactic Acid Bacteria-Treated Milk Raw Materials The powdered lactic acid bacteria-treated milk raw materials (invention samples 2-a and 2-b) produced in Experimental Example 2(1) and the powdered milk raw material not treated with lactic acid bacteria (control sample) were analyzed for aroma components using the headspace solid-phase microextraction method of gas chromatography-mass spectrometry described above, as in Experimental Example 1(2). The analytical value (area value of the chart) of the aroma components of the control sample was set to 1.0, and the analytical values ​​of the aroma components of inventive samples 2-a and 2-b were calculated as relative values. The results are shown in Table 4.

[0089]

[0090] As shown in Table 4, the powdered lactic acid bacteria-treated milk raw materials (inventive samples 2-a and 2-b) tended to have lower levels of DMDS and DMTS, which are indicators of protein deterioration, compared to the powdered milk raw material not treated with lactic acid bacteria (control sample). On the other hand, inventive samples 2-a and 2-b, diacetyl and acetoin tended to increase compared to the control sample. Furthermore, inventive samples 2-a and 2-b, nonanal and δ-decalactone tended to remain almost unchanged compared to the control sample.

[0091] The results of Experimental Example 1 (2) and Experimental Example 2 (2) showed that treating high-protein milk raw materials with lactic acid bacteria reduced DMDS and DMTS, which are indicators of protein deterioration, and increased diacetyl and acetoin, which are indicators of fermentation odor. It was also confirmed that drying these liquid samples to prepare powdered (solid) samples did not affect the tendency for DMDS and DMTS to decrease and diacetyl and acetoin to increase.

[0092] (3) Analysis of free amino acids in powdered lactic acid bacteria-treated milk raw materials Using the ultra-high performance liquid chromatography mass spectrometry method described above, the powdered lactic acid bacteria-treated milk raw materials (invention samples 2-a and 2-b) produced in Experimental Example 2(1) and the powdered milk raw material not treated with lactic acid bacteria (control sample) were analyzed for free amino acids (histidine (His), asparagine (Asn), serine (Ser), glutamine (Gln), glycine (Gly), arginine (Arg), aspartic acid (Asp), glutamic acid (Glu), threonine (Thr), alanine (Ala), proline (Pro), lysine (Lys), cysteine ​​(Cys), tyrosine (Tyr), methionine (Met), isoleucine (Ile), valine (Val), leucine (Leu), phenylalanine (Phe), tryptophan (Trp), citrulline (Cit), γ-aminobutyric acid (GABA), and ornithine (Orn)). The results are shown in Tables 5-1 to 5-4.

[0093]

[0094]

[0095]

[0096]

[0097] As shown in Tables 5-1 to 5-4, it was confirmed that the powdered lactic acid bacteria-treated milk raw materials (invention samples 2-a and 2-b) had an overall increased amount of free amino acids compared to the powdered milk raw material not treated with lactic acid bacteria (control sample).

[0098] (4) Sensory evaluation of powdered lactic acid bacteria-treated milk raw materials Aqueous solutions were prepared for the powdered lactic acid bacteria-treated milk raw materials (invention samples 2-a and 2-b) produced in (1) above and the control sample, each with a total solids content of 10% by mass. A five-person expert panel evaluated these solutions using a paired comparison method with the control sample according to the method described above to evaluate the protein odor and clean aftertaste of invention samples 2-a and 2-b. The average scores of the five expert panelists are shown in Table 6.

[0099]

[0100] As shown in Table 6, the powdered lactic acid bacteria-treated milk raw materials (invention samples 2-a and 2-b) had a reduced protein odor and a clean aftertaste compared to the powdered milk raw material not treated with lactic acid bacteria (control sample). Furthermore, neither invention sample 2-a nor 2-b had a sour taste. Based on the results shown in Table 4, it is believed that the reduction in DMDS and DMTS, which are factors in the protein odor, and the increase in diacetyl and acetoin exerted a masking effect, resulting in a reduced protein odor and a clean aftertaste.

[0101] Experimental Example 3. Production of a liquid lactic acid bacteria-treated high-protein milk raw material using WPC as a milk raw material and its evaluation (1) Production of a liquid lactic acid bacteria-treated high-protein milk raw material WPC was dissolved in warm water (60°C) to prepare a WPC liquid with a total solid content of 10% by mass (milk-derived protein content per 100 parts by mass of total solids: 80 parts by mass). This WPC liquid was heat sterilized (reaching 70°C) and then cooled (40°C) to prepare a heat-sterilized WPC liquid. A predetermined amount (10 6 ~10 8cfu / ml) and stirred at the temperature and for the time shown in Table 7 to prepare lactic acid bacteria-treated WPC solutions having the pH shown in Table 7. None of these lactic acid bacteria-treated WPC solutions formed curd and were in liquid form. Next, these lactic acid bacteria-treated WPC solutions were heated (up to 60°C) and then cooled (to 10°C or below) to produce liquid lactic acid bacteria-treated WPC (lactic acid bacteria-treated high-protein milk raw material). Hereinafter, these are referred to as "lactic acid bacteria-treated milk raw material" (invention samples 3-a to 3-f).

[0102]

[0103] (2) Analysis of Aroma Components of Liquid Lactic Acid Bacteria-Treated Milk Raw Materials Using the headspace solid-phase microextraction method of gas chromatography-mass spectrometry described above, aroma components were analyzed for the lactic acid bacteria-treated milk raw materials (inventive samples 3-a to 3-f) produced in Experimental Example 3(1) and a heat-sterilized WPC liquid (a milk raw material not treated with lactic acid bacteria) (control sample) prior to lactic acid bacteria treatment, as in Experimental Example 1(2). As in Experimental Example 1(2), the aroma components selected were DMDS and DMTS (both indicators of protein degradation), nonanal (an indicator of lipid degradation), diacetyl (an indicator of fermented aroma), acetoin (an indicator of fermented aroma), and δ-decalactone (an indicator of milkiness). The analytical values ​​of the aroma components of the control sample (area value of the chart) were set to 1.0, and the analytical values ​​of the aroma components of inventive samples 3-a to 3-f were calculated as relative values. The results are shown in Table 8.

[0104]

[0105] As shown in Table 8, the liquid lactic acid bacteria-treated milk raw materials (inventive samples 3-a to 3-f) tended to have reduced levels of DMDS and DMTS, which are indicators of protein deterioration, and nonanal, which is an indicator of lipid deterioration, compared to the liquid milk raw material not treated with lactic acid bacteria (control sample). On the other hand, the inventive samples 3-a to 3-f tended to have increased levels of diacetyl and / or acetoin, which are indicators of fermented aroma, compared to the control sample. Furthermore, the inventive samples 3-a to 3-f tended to have almost no change in δ-decalactone compared to the control sample.

[0106] (3) Sensory evaluation of liquid lactic acid bacteria-treated milk raw material As in Experimental Example 1 (3), a panel of five experts evaluated the protein odor and clean aftertaste of inventive samples 3a to 3f using a paired comparison method with a control sample. The average scores of the five experts are shown in Table 9.

[0107]

[0108] As shown in Table 9, the liquid lactic acid bacteria-treated milk raw materials (inventive samples 3-a to 3-f) all had a reduced protein odor and a clean aftertaste compared to the liquid non-lactic acid bacteria-treated milk raw material (control sample). Furthermore, inventive samples 3-a, 3-c, 3-e, and 3-f all had no sourness, while inventive samples 3-b and 3-d all had a slight sourness. Based on the results shown in Table 8, it is likely that the reduction in DMDS and DMTS, which are factors contributing to the protein odor, and the increase in diacetyl and acetoin provided a masking effect, resulting in a reduced protein odor and a clean aftertaste. Furthermore, it was confirmed that when the pH after lactic acid bacteria treatment was 6 or higher, no sourness was perceived, whereas when the pH was lower than 6, a sourness was perceived.

[0109] Experimental Example 4. Production and Evaluation of Powdered Lactic Acid Bacteria-Treated High-Protein Milk Raw Material Using WPC as a Milk Raw Material (1) Production of Powdered Lactic Acid Bacteria-Treated High-Protein Milk Raw Material Among the liquid lactic acid bacteria-treated milk raw materials (invention samples 3-a to 3-f) produced in Experimental Example 3(1), inventive sample 3-a and a heat-sterilized WPC liquid (milk raw material not treated with lactic acid bacteria, control sample) before lactic acid bacteria treatment were spray-dried (inlet air temperature: 180-185°C, exhaust air temperature: 80-85°C) to produce powdered (solid) lactic acid bacteria-treated WPC (lactic acid bacteria-treated high-protein milk raw material, inventive sample 4-a) and powdered milk raw material not treated with lactic acid bacteria (control sample). Hereinafter, these are referred to as the "powdered lactic acid bacteria-treated milk raw material" (invention sample 4-a) and the "powdered milk raw material not treated with lactic acid bacteria" (control sample).

[0110] (2) Analysis of Aroma Components of Powdered Lactic Acid Bacteria-Treated Milk Raw Material Aqueous solutions were prepared from the powdered lactic acid bacteria-treated milk raw material (invention sample 4-a) produced in Experimental Example 4(1) and the powdered non-lactic acid bacteria-treated milk raw material (control sample) so that the total solid content was 10% by mass. Then, as in Experimental Example 1(2), the aroma components of these aqueous solutions were analyzed using the headspace solid-phase microextraction method of gas chromatography-mass spectrometry described above.

[0111] The analytical value of the aroma components of the control sample (area value of the chart) was set to 1.0, and the analytical value of the aroma components of the invention sample 4-a was calculated as a relative value. The results are shown in Table 10.

[0112]

[0113] As shown in Table 10, the powdered lactic acid bacteria-treated milk raw material (invention sample 4-a) tended to have a decrease in DMDS and DMTS, which are indicators of protein deterioration, compared to the milk raw material not treated with lactic acid bacteria (control sample). On the other hand, the inventive sample 4-a tended to have an increase in diacetyl and acetoin compared to the control sample. Furthermore, the inventive sample 4-a tended to have almost no change in δ-decalactone compared to the control sample.

[0114] The results of Experimental Examples 3(2) and 4(2) showed that treating high-protein milk raw materials with lactic acid bacteria reduced DMDS and DMTS, which are indicators of protein deterioration, and increased diacetyl and acetoin, which are indicators of fermentation odor. It was also confirmed that drying these liquid samples to prepare powdered (solid) samples did not significantly affect the tendency for DMDS and DMTS to decrease and diacetyl and acetoin to increase.

[0115] (3) Analysis of free amino acids in powdered lactic acid bacteria-treated milk raw material Using the ultra-high performance liquid chromatography mass spectrometry method described above, free amino acids (histidine (His), asparagine (Asn), serine (Ser), glutamine (Gln), glycine (Gly), arginine (Arg), aspartic acid (Asp), glutamic acid (Glu), threonine (Thr), alanine (Ala), proline (Pro), lysine (Lys), cysteine ​​(Cys), tyrosine (Tyr), methionine (Met), isoleucine (Ile), valine (Val), leucine (Leu), phenylalanine (Phe), tryptophan (Trp), citrulline (Cit), and γ-aminobutyric acid (GABA)) were analyzed for inventive sample 4-a produced in Experimental Example 4(1) and a control sample. The results are shown in Tables 11-1 to 11-4.

[0116]

[0117]

[0118]

[0119]

[0120] As shown in Tables 11-1 to 11-4, it was confirmed that the powdered lactic acid bacteria-treated milk raw material (invention sample 4-a) had an overall increased amount of free amino acids compared to the powdered milk raw material not treated with lactic acid bacteria (control sample).

[0121] (4) Sensory evaluation of powdered lactic acid bacteria-treated milk raw material Aqueous solutions were prepared for the powdered lactic acid bacteria-treated milk raw material (invention sample 4a) produced in (1) above and the control sample so that the total solids content was 10% by mass. Five expert panelists evaluated these solutions using a paired comparison method with the control sample according to the method described above to evaluate the protein odor and clean aftertaste of invention sample 4-a. The average scores of the five expert panelists are shown in Table 12.

[0122]

[0123] As shown in Table 12, the powdered lactic acid bacteria-treated milk raw material (invention sample 4-a) had a reduced protein odor and a clean aftertaste compared to the powdered milk raw material not treated with lactic acid bacteria (control sample). In addition, inventive sample 4-a had almost no sourness.

[0124] Judging from the results shown in Table 10, it is thought that the reduction in DMDS and DMTS, which are one of the causes of protein odor, and the increase in diacetyl and acetoin exerted a masking effect, thereby reducing the protein odor and providing a clean aftertaste.

[0125] Experimental Example 5. Production and evaluation of high-protein milk beverages incorporating powdered lactic acid bacteria-treated milk ingredients (1) Production of high-protein milk beverages High-protein milk beverages (invention beverage, control beverage) were produced by blending the powdered lactic acid bacteria-treated milk ingredient produced in Experimental Example 2 (invention sample 2-a) or powdered milk ingredient not treated with lactic acid bacteria (control sample). Specifically, the invention beverage and control beverage were produced as follows.

[0126] (1-1) Production of the Invention Beverage: Inventive Sample 2-a and concentrated skim milk (total solids content: approximately 30% by mass) were mixed to prepare a blended liquid with a protein content of approximately 8% by mass. Sodium bicarbonate (sodium bicarbonate) was then added to this blended liquid, and the pH was adjusted to 6.7, equivalent to that of the control beverage described below. This blended liquid was then heated (65°C) and homogenized (first-stage pressure: 10 MPa, second-stage pressure: 5 MPa), followed by heat sterilization (reaching 90°C) and cooling (to 10°C or below) to produce the invention beverage (protein content: 8% by mass).

[0127] (1-2) Production of Control Beverage The control sample and concentrated skim milk (total solids content: approximately 30% by mass) were mixed to prepare a liquid preparation with a protein content of approximately 8% by mass. This liquid preparation was then heated (65°C) and homogenized (first stage pressure: 10 MPa, second stage pressure: 5 MPa), then heat sterilized (reaching 90°C) and cooled (to 10°C or below) to produce a control beverage (protein content: 8% by mass).

[0128] (2) Sensory Evaluation of the Invention Beverage A panel of 15 experts evaluated the invention beverage using a paired comparison method with a control beverage, evaluating the protein odor, refreshing feeling (refreshing aftertaste), fresh milk aroma, and heated milk aroma.

[0129] "Fresh milk aroma" refers to the original milk flavor felt from unheated (unpasteurized) milk (raw milk). "Heated milk aroma" refers to the burnt flavor felt from heated (pasteurized) milk. Each expert panel confirmed these flavors in advance, discussed them with each other, and standardized their internal standards. According to the following criteria, each expert panel scored protein odor, refreshing feeling (refreshing aftertaste), fresh milk aroma, and heated milk aroma, and calculated the average score to determine the overall evaluation.

[0130] [Protein odor] 3: Reduced protein odor compared to the control sample 2: Same level of protein odor compared to the control sample 1: Increased protein odor compared to the control sample [Clean aftertaste] 3: No unpleasant aftertaste and very clean compared to the control sample 2: Same level of aftertaste (unpleasant taste) compared to the control sample 1: Unpleasant aftertaste and less clean compared to the control sample [Fresh milk aroma] 3: Stronger fresh milk aroma compared to the control sample 2: Same level of fresh milk aroma compared to the control sample 1: Weaker fresh milk aroma compared to the control sample [Heated milk aroma] 3: Weaker heated milk aroma compared to the control sample 2: Same level of heated milk aroma compared to the control sample 1: Stronger heated milk aroma compared to the control sample

[0131]

[0132] As shown in Table 13, the inventive beverage had a reduced protein odor, a clean aftertaste, a stronger fresh milk aroma, and a reduced heated milk aroma compared to the control sample.

Claims

1. (1) preparing a milk fluid from a milk raw material, the milk fluid having a total solid content of 5 to 15% by mass and a milk-derived protein content of 50 parts by mass or more per 100 parts by mass of the total solid content; (2) A step of adding lactic acid bacteria to the milk fluid and maintaining the pH in the range of 5.2 to 6.5 to obtain a lactic acid bacteria-treated milk fluid having a pH in the range. A method for producing a high-protein dairy raw material having the above structure.

2. moreover, (3-1) A step of concentrating the lactic acid bacteria-treated milk fluid, or a step of concentrating and drying the lactic acid bacteria-treated milk fluid, A method for producing the high-protein dairy raw material according to claim 1.

3. moreover, (3-2) A step of drying the lactic acid bacteria-treated milk fluid. A method for producing the high-protein dairy raw material according to claim 1.

4. The dairy fluid does not contain casein but contains whey protein as a milk-derived protein. A method for producing a high-protein milk raw material according to any one of claims 1 to 3.

5. The dairy fluid contains casein or casein and whey protein as a milk-derived protein, The step (2) is a step of using lactic acid bacteria to maintain the pH in the range of 6.0 to 6.5 to obtain a lactic acid bacteria-treated milk fluid having a pH in the range. A method for producing a high-protein milk raw material according to any one of claims 1 to 3.

6. The method according to claim 4, wherein the high-protein dairy raw material is at least one selected from whey protein concentrate (WPC) and whey protein isolate (WPI).

7. 6. The method of claim 5, wherein the high protein dairy raw material is at least one selected from milk protein concentrate (MPC), milk protein isolate (MPI), and micellar casein concentrate (MCC).

8. A liquid lactic acid bacteria-treated high-protein milk raw material having a milk-derived protein content of 50 parts by mass or more per 100 parts by mass of total solids, Contains at least killed lactic acid bacteria, diacetyl, and 3-hydroxy-2-butanone; Characterized in that the pH is in the range of 5.2 to 6.5, The lactic acid bacteria-treated high-protein dairy raw material.

9. The milk-derived protein does not contain casein but contains whey protein. The high-protein milk raw material treated with lactic acid bacteria according to claim 8.

10. The milk-derived protein contains casein or casein and whey protein, The pH is in the range of 6.0 to 6.5; The high-protein milk raw material treated with lactic acid bacteria according to claim 8.

11. A semi-solid or solid lactic acid bacteria-treated high-protein milk raw material, which is obtained by concentrating and / or drying the liquid lactic acid bacteria-treated high-protein milk raw material according to any one of claims 8 to 10.

12. A method for producing a food or drink, comprising a step of incorporating a high-protein milk raw material obtained by the production method according to any one of claims 1 to 3 into the food or drink.

13. A food or drink comprising the lactic acid bacteria-treated high-protein milk raw material according to any one of claims 8 to 10.

14. (1) preparing a milk fluid from a milk raw material, the milk fluid having a total solid content of 5 to 15% by mass and a milk-derived protein content of 50 parts by mass or more per 100 parts by mass of the total solid content; (2) A step of adding lactic acid bacteria to the milk fluid and maintaining the pH in the range of 5.2 to 6.5 to obtain a lactic acid bacteria-treated milk fluid having a pH in the range. A method for improving the flavor of a high-protein dairy raw material.